Help with error: TypeError: cannot concatenate 'str' and 'int' objects

Hi:
I would like to be able to solve this communication issue between Calibre and my device without deleting the books.db of my Sony Prs-T1.

I've been using Calibre for a while and I'm happy with it, but I had a couple of problems in the past trying to communicate with the device.
To fix them I always deleted the books.db (the problem was "bad image" or something like that, and the solution Sony suggested was to delete the db)
The thing is that after deleting the books.db you loose all the highlights and annotations and also all the names and the library order or the different collections (I have now 52 collections)

Is there a way to solve this time the issue without deleting the books.db?

This is the communication error with the device:
Traceback (most recent call last):
File "site-packages\calibre\gui2\device.py", line 85, in run
File "site-packages\calibre\gui2\device.py", line 470, in _books
File "site-packages\calibre\devices\prst1\driver.py", line 197, in books
TypeError: cannot concatenate 'str' and 'int' objects

Thank you for answering.
Now, after rebuilding the books.db, recreating manually all the collections and adding several books, all seemed OK, but then, suddenly, I got a new error and calibre can't communicate with the device: